The present invention relates to a sliding resin composition comprising a synthetic resin which contains polytetrafluoroethylene (hereinafter referred to as “PTFE”) as a solid lubricant and an inorganic compound having oil-absorptivity.
Hitherto, there have been used sliding resin compositions comprising various synthetic resins which contain PTFE as a solid lubricant. As these sliding resin compositions, proposed are those which comprise various synthetic resins which further contain a phosphate in addition to PTFE. When sliding resin compositions containing PTFE and a phosphate are used, the phosphate promotes transfer adhesion of PTFE to the surface of a counter member during sliding to form a transfer adhesion film of PTFE on the surface of the counter member, resulting in improvement of sliding characteristics of resin sliding member under dry condition.
For example, Japanese Patent No. 2777724 (Patent Document 1) discloses use of calcium phosphate, magnesium phosphate, barium phosphate, or lithium phosphate as an inorganic compound having function to form a transfer adhesion film of PTFE. However, recently, as the inorganic compounds, there are also known inorganic compounds such as lithium tertiary phosphate, calcium tertiary phosphate, calcium hydrogenphosphate or anhydride thereof, magnesium hydrogenphosphate or anhydride thereof, lithium pyrophosphate, calcium pyrophosphate, magnesium pyrophosphate, lithium metaphosphate, calcium metaphosphate, magnesium metaphosphate, lithium carbonate, magnesium carbonate, calcium carbonate, strontium carbonate, barium carbonate, calcium sulfate, and barium sulfate.
Furthermore, JP-A-9-136987 (Patent Document 2) and JP-A-2004-83640 (Patent Document 3) disclose to impart functions such as absorption and retention of liquids (e.g., lubricating oil) to the sliding resin compositions by using calcium carbonate having porous structure.    Patent Document 1: Japanese Patent No. 2777724    Patent Document 2: JP-A-9-136987    Patent Document 3: JP-A-2004-83640